Option for slots & 'book all day' without addons

Right now if one needs to have slots and the option to book the whole day, he can use addons. But if you have many slots, only the first one will show as available when selecting the whole day (with addons).

It would make a lot of sense to have a an option (checkbox) for people to book 'all day'. Something like in the backend of Edit Appointment. This would be good to have it on a product base (not global)